An intracavitary ultrasound probe is designed to observe an esophageal wall, an intestinal wall, and the like from inside by inserting the probe inside the human body through the mouth, anus, and the like of a human body. Accordingly, a flexible section which can be freely bent into a complicated shape corresponding to that of the tubular organ being examined, such as an intestinal canal, has been variously devised as mentioned below.
First, as disclosed in Japanese Patent Publication No. 2790253 (first conventional technique), an ultrasound probe of the electronic scan type includes an ultrasound transducer group in which a transducer array for transmitting and receiving ultrasound is formed by a plurality of transducers and a flexible printed circuit board formed in a longitudinal direction of the transducers at a predetermined angle relative to the ultrasound transducer group, in which an electrode extraction lead for acquiring a signal from each ultrasound transducer of the ultrasound transducer group is formed on one end.
As shown in FIG. 4(a) of the above-referenced patent document, the printed circuit board is formed so that the section in which the ultrasound transducer group is arranged is rectangular, and an electrode extracting section joined with the rectangular section is formed so that the surface electrode pattern is inclined at a certain angle relative to the longitudinal direction of the ultrasound transducer group. At the same time, the outer shape of the printed circuit is carved out, being inclined at a certain angle similar to the pattern. A portion of the circuit board on which the ultrasound transducer group is mounted has adhering sections at both ends, and an adhering section is also provided on one end of the printed circuit board on which the electrode pattern is formed. When the printed circuit is made into a cylindrical shape and the respective adhering sections are adhered with a bond, the electrode pattern is spirally formed and a gap provided between the adhering sections of the printed circuit board is also formed spirally. With this construction, the printed circuit board can be bent without being broken.
Further, as shown in FIG. 8(a) of the above-referenced patent document, the printed circuit board divides the ultrasound transducer group into blocks, and the electrode extracting section of the printed circuit board is lead in directions of θ, −θ, θ, −θ, . . . in turn at each block. By thus forming the ultrasound transducer group and the printed circuit board into a cylindrical shape, the printed circuit board is constructed in a meshed pattern. The end connected with a lead wire is slightly shifted, so that the position of a land attached with the lead wire does not overlap with a land of another printed circuit board in weaving the printed circuit board. Further, the end connected with the lead wire is provided with an adhering section for adhering each of the printed circuit boards. The printed circuit board, being one undivided plate, can be made more flexible by forming it into a meshed pattern.
Next, as disclosed in Japanese Unexamined Utility Model Patent Publication No. Hei. 5-13408 (second conventional technique), an ultrasound sensor is mounted at the end of a flexible body, and a signal from the ultrasound sensor is transmitted to a cable on the end by a flexible printed circuit (FPC). The FPC is provided with a plurality of slits in its longitudinal direction and is wound in its width direction. A coil spring connected to a GND of the ultrasound sensor surrounds it.
However, according to the first conventional technique, the printed circuit board is formed as one plate. Even in the example of block division, the printed circuit boards are adhered to each other and are substantially made into one plate.
Since the printed circuit board is thus formed as one plate, the range of flexibility of the intracavitary probe is limited by a stiffness of the printed circuit board when it is inserted into the object's body cavity; and, due to this limitation in the flexibility, the intracavitary probe cannot be sufficiently bent along a complicatedly curving tubular organ in some cases. Accordingly, there is a possibility that a part of the intracavitary ultrasound probe will touch a wall of the tubular organ so as to cause pain to the object, which has not been considered.
Further, according to the second conventional technique, the plurality of slits are provided on the FPC in the longitudinal direction and are surrounded with a coil spring 7, which occupies extra space. Therefore, this approach has provided an obstacle to the desire for miniaturizing the probe, increasing the number of channels, and improving the flexibility of the flexible section.
Moreover, an ultrasound apparatus is used not only independently for diagnosis, but also with a treatment device. For example, treatment is conducted by irradiating a strong ultrasound to cauterize a cancer cell. When the ultrasound diagnostic apparatus according to the present invention is used with an electronic device, such as a treatment device, it is also necessary to take into consideration the need to deal with noise infiltrating from the electronic device into the ultrasound probe.